Int 21/AX=7302h

Windows95 - FAT32 - Get_ExtDPB - GET EXTENDED DPB

AX = 7302h
DL = drive number (00h=default, 01h=A:, etc.)
ES:DI -> buffer for returned data (see #01786)
CX = length of buffer (003Fh for Windows95)
SI = signature (undocumented, must be F1A6h to get device driver
address and next-DBP pointer) (see #01787)

Return:
CF clear if successful
ES:DI buffer filled
CF set on error
AX = error code
0018h bad buffer length

See Also: AX=7303h - AX=7304h - AH=1Fh - AH=32h

Format of Get_ExtDPB data buffer: Offset Size Description (Table 01786) 00h WORD (call) length of following data (003Dh) 02h 61 BYTEs (ret) drive parameter block (DPB) (see #01787)

Format of Extended Drive Parameter Block: Offset Size Description (Table 01787) 00h 24 BYTEs standard DOS 4+ DPB 18h BYTE "dpb_flags" (undocumented) FFh force media check 19h DWORD pointer to next DPB (see note) 1Dh WORD cluster at which to start search for free space when writing, usually the last cluster allocated 1Fh WORD number of free clusters on drive, FFFFh = unknown 21h WORD high word of free cluster count 23h WORD active FAT/mirroring

bit 7:
Do not mirror active FAT to inactive FATs

bits 6-4:
Reserved (0)

bits 3-0:
The 0-based FAT number of the active FAT (only meaningful if mirroring disabled) 25h WORD sector number of file system information sector, or FFFFh for none (see also #01788) 27h WORD sector number of backup boot sector, or FFFFh for none 29h DWORD first sector number of the first cluster 2Dh DWORD maximum cluster number 31h DWORD number of sectors occupied by FAT 35h DWORD cluster number of start of root directory 39h DWORD cluster number at which to start searching for free space

Notes: Except for offset 18h, all of the first 33 bytes are identical to the standard DOS 4-6 DPB. Unless the proper value is given in SI on entry to "Get_ExtDBP", the next-DPB pointer and device driver address are set to 0000h:0000h

See Also: #01786 - #01395 at AH=32h - #01664

Format of File System Information structure: Offset Size Description (Table 01788) 00h DWORD signature 61417272h 04h DWORD number of free clusters (FFFFFFFFh if unknown) 08h DWORD most recently allocated cluster 0Ch 12 BYTEs reserved

See Also: #01787

Category: DOS Kernel - Int 21h - W

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